In general, in buildings such as office buildings, industrial buildings, and apartments, various plumbing systems are installed. Such plumbing systems are used with thermal insulation covers installed not only for keeping the plumbing systems warm or cool but also for extension of the lifetimes of the plumbing systems and their appearance designs. Such thermal insulation covers are mainly used for valves, T-shaped pipes, straight pipes, and so on of plumbing systems.
Especially, in power plants (such as nuclear power plants and steam power plants), petrochemical plants, and the like, high-temperature high-pressure steam generated by a boiler provides a torque to a turbine to finally produce electric energy, and high-temperature high-pressure stream or hot water is transported in each system through a plumbing fixture at high speed. In this transport process, fluid friction, cavitation, and the like in pipes may thin the pipes, resulting in a safety accident in a system operating normally. For this reason, during planned preventive maintenance on power generating facilities, pipe thinning (a state where the walls of pipes have thinned due to corrosion and the like) is checked to ascertain the integrity of each facility.
Such pipe thinning phenomenon may cause pin holes in pipes as time goes on, resulting in nasty accidents. For this reason, once a year, planned protective maintenance is carried out on pipes to inspect thinning, and its result is recorded and reported.
When such thinning inspection is performed, in a case where pipes are covered with existing insulating materials, metal protective covers (or finishing covers), the insulating materials, and the like used to finish the outsides of the pipes are sequentially removed, and then the thinning inspection is performed. After this thinning inspection is performed, new insulating materials are attached, and the pipes are finished with protective covers.
The method of attaching insulating materials after a thinning inspection has problems in which the amount of disposal of insulating materials and protective covers which are removed every year causes huge waste of materials and if insulating materials are erroneously attached, thermal notches occur and thus thermal stress increases, whereby the thinning phenomenon remarkably progresses at those parts, resulting in a decrease in the lifetime of the whole plumbing.
A method of overcoming those problems is shown in Korea Patent Laid-Open Publication No. 10-1184392 (Sep. 13, 2012). In Korea Patent Laid-Open Publication No. 10-1184392 (Sep. 13, 2012), an insulation system for plumbing has elbow insulating units, T-fitting insulating units, straight-pipe insulating units, and flange insulating units, wherein each insulating unit has two split bodies, and each split body is composed of a plurality of insulating layers and is covered with a metal finishing cover (or a protecting cover), and the disclosed insulating-material protecting covers are configured with plates having curved surfaces, and are brought into contact with the plumbing so as to cover the plumbing, and are assembled by clamps or the like.
However, the protecting covers having the above-described configuration have low stiffness and thus are likely to be bent. Therefore, it has problem sin which thermal notches are likely to occur at assembly parts, and penetration of water and the like from the assembly parts is easy and deteriorates thermal insulation performance, and damage such as corrosion is likely to occur, and has a problem in which the assembly accuracy decreases.